Fiber-reinforced organic polymer aerogel

ABSTRACT

A fiber-reinforced aerogel is disclosed. The aerogel can include a porous organic polymer matrix and fibers included in the porous organic polymer matrix. The aerogel can include a thermal conductivity of less than or equal to 60 mWIm·K at a temperature of 20° C., at least a bimodal pore size distribution with a first mode of pores having an average pore size of less than or equal to 50 nanometers (nm) and a second mode of pores having an average pore size of greater than 50 nm, and a planar shape having a thickness of 5 millimeters (mm) or less and is capable of being rolled up into a roll, wherein the fibers form a woven fiber matrix.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.17/061,992, filed Oct. 2, 2020, which is a continuation of U.S.application Ser. No. 16/344,332, filed Apr. 23, 2019 (now U.S. Pat. No.10,836,880), which claims benefit to U.S. Provisional Application No.62/412,145, filed Oct. 24, 2016. The referenced applications areincorporated into the present application by reference.

BACKGROUND OF THE INVENTION A. Field of the Invention

The present disclosure relates to the field of aerogels. In particular,the invention concerns a fiber-reinforced organic polymer aerogel havingat least bimodal pore size distribution with a first mode of poreshaving an average pore size of less than or equal to 50 nanometers (nm)and a second mode of pores having an average pore size of greater than50 nm.

B. Description of Related Art

An aerogel is a porous solid that is formed from a gel, in which theliquid that fills the pores of the gel has been replaced with a gas(e.g., air). Shrinkage of the gel's solid network during drying isnegligible or altogether prevented due to the minimization of orresistance to the capillary forces acting on the network as the liquidis removed. In order to prevent shrinking during drying, however, timeconsuming, expensive, and/or complicated processes are typically usedsuch as freeze-drying or super-critical drying (See, U.S. Pat. No.5,705,535). The dried aerogel network is typically comprised ofinorganic particles (e.g., silica-based, titania-based, zirconia-based,alumina-based, hafnia-based, yttria-based, or ceria-based aerogels) orpolymer particles (polymer-based aerogels) (See, U.S. Patent ApplicationPublication No. 2015/0017860). These aerogels are generallycharacterized as having high porosity (about 94-99%), single-mode poresize distribution, low density, and high specific surface area. Highporosity confers a number of useful properties to aerogels, includinghigh surface area, low refractive index, low dielectric constant, lowthermal-loss coefficient, and low sound velocity.

However, conventional aerogels lack mechanical durability. The lack ofdurability can have a negative impact on production scale-up, largescale manufacturing, conformation to irregular surfaces, or maintainingintegrity in dynamic conditions. Recent efforts to improve upon thedurability of aerogels, while still maintaining good thermal andflexible properties, have been focused on internally reinforcingaerogels. For example, U.S. Patent Application Publication No.2002/0094426 discloses reinforced aerogel blankets that use fibers inthe form of a lofty batting to reinforce the aerogel. In other examples,U.S. Patent Application Publication No. 2015/0017860 and U.S. Pat. No.8,214,980, each disclose the use of woven and non-woven fibrousmaterials to support aerogels. It is believed that these and othercurrently available fiber-reinforced aerogels have a single-mode poresize distribution in the solid aerogel network, which may influence themechanical properties, causing the aerogels to become more brittle thandesired, which can cause aerogel-fiber adhesion problems, dusting, andhandling issues. Further, complicated drying processes (e.g.,super-critical drying) are needed to prevent the aerogel network fromcollapsing.

The currently available silica-based fiber-reinforced aerogels use fibermaterials for reinforcement that are themselves mechanically weak and oflow density. This is done in an attempt to avoid breaking and dusting ofthe aerogel matrix by the fiber material when wrapping the aerogelaround an object to be insulated (a pipe, for instance). A strongerfiber material can cause damage to the relatively weak silica-basedaerogel. The weakness of the fiber material and silica aerogels resultsin an overall weak fiber-reinforced polymer aerogel.

SUMMARY OF THE INVENTION

A discovery has been made that provides a solution to the aforementionedproblems associated with currently-available fiber-reinforced aerogels.The discovery is premised on the creation of a multi-modal pore sizedistribution (i.e., a pore size distribution having at least two modesof pore size) throughout the solid or dried aerogel network, and usingrelatively strong fiber materials to reinforce an organic polymeraerogel matrix. In particular, the solid aerogel network can have atleast two distinct populations of pore sizes, one with an averagediameter smaller than 50 nm, and one with an average diameter largerthan 50 nm. In some instances, a trimodal pore size distribution can becreated where the third pore size mode has an average diameter ofgreater than 1 micron (μm). Without wishing to be bound by theory, it isbelieved that the multi-modal pore size structure of the aerogel networkis created by particular polymers (e.g., resorcinol formaldehyde) andfibers (e.g., non-woven polyester fibers) that can cause differentnucleation events of the solubilized polymers during the formation ofthe gel-network. By way of example, and without wishing to be bound bytheory, resorcinol formaldehyde can cross-link during processing, whichcan serve to limit the size of some of the resulting particles, whilethe presence of the fibers can provide different nucleation eventsresulting in polymer particles with varying sizes. This can result in agelled-network of polymer particles with different sizes. Once theliquid-phase is removed via drying, the resulting aerogel network has amulti-modal pore size distribution due to the different polymer particlesizes present in the solid aerogel network. Notably, the presence ofvarying particle sizes in the gel can help prevent network collapseduring drying, which allows the aerogels of the present invention to beproduced by processes such as thermal drying or evaporative air dryingin addition to the more commonly used freeze-drying and super-criticaldrying processes. The use of thermal and/or evaporative air dryingprovides for a more cost- and time-efficient process that can bescalable to meet large scale manufacturing needs. Even further, thepresence of the multi-modal pore structure can help reduce the thermalconductivity of the fiber-reinforced aerogels of the present inventionto less than or equal to 30 mW/m·K at a temperature of 20° C. Thefiber-reinforced organic polymer aerogels disclosed herein have superiormechanical properties to prior art fiber-reinforced aerogels.Mechanically strong fiber materials are used, and, surprisingly, thefiber materials do not negatively impact thermal conductivity. Thecombination of the strong fiber materials and the organic polymeraerogel matrices herein results in aerogels that are much stronger andless compressible than currently available reinforced aerogels, whilemaintaining good thermal properties. Notably, and as exemplified in theExamples, the fiber-reinforced organic polymer aerogel has less weightloss when used (e.g., pipe wrapping) as compared to commerciallyavailable silica gel aerogels. In some embodiments, the fiber-reinforcedorganic polymer aerogel can have a weight loss of less than 0.5%, lessthan 0.4%, less than 0.3%, less than 0.2%, less than 0.1% duringhandling.

Disclosed herein is a fiber-reinforced organic polymer aerogelcomprising a non-fibrous organic polymer matrix and fibers comprised inthe non-fibrous organic polymer matrix. The aerogel comprises a thermalconductivity of less than or equal to 30 mW/m·K at a temperature of 20°C. and has an at least bimodal pore size distribution (i.e., a pore sizedistribution having at least two modes) with a first mode of poreshaving an average pore size of less than or equal to 50 nm and a secondmode of pores having an average pore size of greater than 50 nm. In someembodiments, the fiber-reinforced organic polymer aerogel has a firstmode of pores with an average pore size from 3 nm to 50 nm and a secondmode of pores with an average pore size from 50 nm to 10 μm. In someembodiments, the fiber-reinforced organic polymer aerogel has a trimodalpore size distribution, where a first mode of pores has an average poresize of 3 nm to 50 nm, a second mode of pores has an average pore sizeof 50 nm to 10 micron (μm, 10,000 nm), and a third mode of pores has anaverage pore size of greater than 10 μm. In particularly preferredembodiments, the polymer matrix of the aerogel is a resorcinolformaldehyde polymer matrix and the fibers are non-woven polyesterfibers. In some embodiments, the first mode of pores have an averagepore size greater than, equal to, or between any two of 3 nm, 5 nm, 10nm, 15 nm, 20 nm, 25 nm, 30 nm, 35 nm, 40 nm, 45 nm, and 50 nm. Thesecond mode of pores can be greater than, equal to, or between any twoof 50, 100, 200, 300, 400, 500, 600, 700, 800, 900, 1000, 5000, 10,000nm.

In some embodiments, the fiber-reinforced organic polymer aerogel has aweight ratio of the organic polymer matrix to the fibers of 50 to 65. Insome embodiments, the weight ratio is 40, 45, 50, 55, 60, 65, 70, 75,80, or 85 or is between any two of those values. The fiber-reinforcedorganic polymer aerogel can have a non-fibrous organic polymer matrixthat can include resorcinol formaldehyde, phenol formaldehyde,polyimide, polyamine, polyamide, poly(amide-imide), poly(amic amide),poly(ether imide), polyphenol, polyalcohol, polyvinyl butryal,polyurethane, polyurea, polycarbonate, polyester, polyether, polyacid,or any combination thereof. Other suitable non-fibrous organic polymermaterials are known to those of skill in the art. In some embodiments,it is contemplated that silica-based and other inorganic-based aerogelsare not used in the fiber-reinforced polymer aerogels of the presentinvention. In some embodiments, the non-fibrous organic polymer matrixcomprises or consists of resorcinol formaldehyde or polyimide. In someembodiments, the non-fibrous organic polymer matrix is a resorcinolformaldehyde polymer matrix. In some embodiments, the non-fibrousorganic polymer matrix is a cross-linked organic polymer matrix.

The fibers comprised in the non-fibrous polymer matrix can be natural,synthetic, semi-synthetic fibers, or combinations thereof. The fiberscan comprise vegetable, wood, animal, mineral, biological fibers, orcombinations thereof. In some particular instances, the fibers cancomprise rayon, bamboo, diacetate, triacetate fibers, polyester fibers,aramid fibers, or combinations thereof. In some embodiments, the fiberscomprise metal fibers, carbon fibers, carbide fibers, glass fibers,mineral fibers, basalt fibers, or combinations thereof. In someembodiments, the fibers comprise thermoplastic polymer fibers, thermosetpolymer fibers, or combinations thereof. Non-limiting examples ofthermoplastic fibers includes fibers of polyethylene terephthalate(PET), a polycarbonate (PC) family of polymers, polybutyleneterephthalate (PBT), poly(1,4-cyclohexylidene cyclohexane-1,4-dicarboxylate) (PCCD), glycol modified polycyclohexyl terephthalate(PCTG), poly(phenylene oxide) (PPO), polypropylene (PP), polyethylene(PE), polyvinyl chloride (PVC), polystyrene (PS), polymethylmethacrylate (PMMA), polyethyleneimine or polyetherimide (PEI) and theirderivatives, thermoplastic elastomer (TPE), terephthalic acid (TPA)elastomers, poly(cyclohexanedimethylene terephthalate) (PCT),polyethylene naphthalate (PEN), polyamide (PA), polysulfone sulfonate(PSS), sulfonates of polysulfones, polyether ether ketone (PEEK),polyether ketone ketone (PEKK), acrylonitrile butyldiene styrene (ABS),polyphenylene sulfide (PPS), co-polymers thereof, or blends thereof.Non-limiting examples of thermoset fibers include a fiber of polyaramid,polyimide, polybenzoxazole, polyurethane, or blends thereof. In someembodiments, the fibers are polyaramid, polyimide, polybenzoxazole,polyurethane, or blends thereof. In some embodiments, the fibers arevinylon. In some embodiments, the fibers are polyester fibers. In someembodiments, the fibers are non-woven. In some embodiments, the fibersform a fiber matrix. In some embodiments, the fiber matrix isdistributed throughout the non-fibrous organic polymer matrix. In someembodiments, the fibers have an average filament cross sectional area of5 μm² to 40,000 μm² and an average length of 20 mm to 100 mm. In someembodiments, the cross sectional area is 5, 10, 15, 20, 25, 50, 100,150, 200, 250, 300, 350, 400, 450, or 500 μm² or between any two ofthose values. In some embodiments, the fibers have an average length ofapproximately 0.1, 0.2, 0.3, 0.4, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10,20, 30, 40, 50, 60, 70, 80, 90, 100, 150, 200, 250, 300, 350, 400, 450,500, 600, 700, 800, 900, 1000, 1500, 2000, 3000, 4000, 5000 mm orbetween any two of those values. In some embodiments, the fiber matrixcomprises felt, batting, non-woven fabric, or a mat.

In some embodiments, the fiber-reinforced organic polymer aerogelsdescribed herein have a thermal conductivity less than or equal to 30mW/m·K at temperatures below, up to, or at 150° C. In some embodimentsthe thermal conductivity is less than or equal to 35 mW/m·K attemperatures below, up to, or at 200° C. In some embodiments, thethermal conductivity is about 10, 11, 12, 13, 14, 15, 16, 17, 18, 19,20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, or 35 mW/m·Kor is between any of these values at temperatures below, up to, or at150° C. or below, up to, or at 200° C. In some embodiments, the thermalconductivity is about 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21,22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, or 35 mW/m·K or isbetween any of these values at temperatures of −200, −150, −100, −50,−20, −10, 0, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130,140, 150, 160, 170, 180, 190, or 200° C. or at temperatures below any ofthose values or between any two of those values.

In some embodiments, the fiber-reinforced organic polymer aerogelsdescribed herein have a density of less than 0.5 g/cm³ or less than 0.25g/cm³ or from 0.1 g/cm³ to 0.5 g/cm³ or from 0.2 g/cm³ to 0.25 g/cm³. Insome embodiments, the fiber-reinforced organic polymer aerogel has adensity of 0.1, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19,0.20, 0.21, 0.22, 0.23, 0.24, 0.25, 0.26, 0.27, 0.28, 0.29, 0.30, 0.31,0.32, 0.33, 0.34, 0.35, 0.36, 0.37, 0.38, 0.39, or 0.40 g/cm³ or betweenany two of those values.

In some embodiments, the fiber-reinforced organic polymer aerogelsdescribed herein have a pore volume of greater than 2 cm³/g or of 2.0,2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, or 3.0 cm³/g or between anytwo of those values.

In some embodiments, the fiber-reinforced organic polymer aerogelsdescribed herein have a surface area of at least 150 m²/g or of 50, 75,100, 125, 150, 200, 210, 220, 230, 240, 250, 260, 270, 280, 290, or 300m²/g or between any two of those values.

In some embodiments, the fiber-reinforced organic polymer aerogelsdescribed herein can have a substantially planar shape and have athickness of 0.5 mm to 25 mm. In some embodiments, the thickness isapproximately 0.5, 1, 2, 3, 4, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50,60, 70, 80, 90, 100, 200, 300, 400, 500, 600, 700, 800, 900, or 1000 mmor between any two of those values. In some embodiments, the aerogel hasa thickness of 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 mm or between any ofthose values.

In some embodiments, the fiber-reinforced organic polymer aerogelsdescribed herein have a tensile strength of at least 2 MPa as measuredin either the machine or cross direction. In some embodiments thetensile strength is 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, or 5 MPa or isbetween any two of those values as measured in the machine direction. Insome embodiments the tensile strength is 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5,or 5 MPa or is between any two of those values as measured in the crossdirection. In some embodiments, the tensile strength is 1, 1.5, 2, 2.5,3, 3.5, 4, 4.5, or 5 MPa or is between any two of those values asmeasured in the machine or cross direction at a temperature of 23° C.

In some embodiments, the fiber-reinforced organic polymer aerogelsdescribed herein have a flex fatigue of at least 50,000, 100,000, or500,000 cycles to failure, or between any two of those values.

Also disclosed is an article of manufacture comprising any of thefiber-reinforced organic polymer aerogels described above. The articleof manufacture may be a thin film, monolith, wafer, blanket, corecomposite material, substrate for radiofrequency antenna, substrate fora sunshield, substrate for a sunshade, substrate for radome, insulatingmaterial for oil and/or gas pipeline, insulating material for liquefiednatural gas pipeline, insulating material for cryogenic fluid transferpipeline, insulating material for apparel, insulating material foraerospace applications, insulating material for buildings, cars, andother human habitats, insulating material for automotive applications,insulation for radiators, insulation for ducting and ventilation,insulation for air conditioning, insulation for heating andrefrigeration and mobile air conditioning units, insulation for coolers,insulation for packaging, insulation for consumer goods, vibrationdampening, wire and cable insulation, insulation for medical devices,support for catalysts, support for drugs, pharmaceuticals, and/or drugdelivery systems, aqueous filtration apparatus, oil-based filtrationapparatus, and solvent-based filtration apparatus, or any combinationthereof. In some embodiments, the article of manufacture is a blanket,which may have a thickness of 5 mm to 10 mm or of about 5, 6, 7, 8, 9,10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 50, 100,500, 1000, 1500, 2000, or 3000 mm or between any two of those values.

Also disclosed is a method of making the fiber-reinforced organicpolymer aerogels of the present invention. The method can include: a)obtaining fibers; b) obtaining a gel precursor solution that can includea first solvent and a polymer precursor (e.g., one or more monomers); c)combining the fibers and the solution; d) forming a polymer gel from thesolution having the fibers included therein; and e) drying the polymergel to form the fiber-reinforced polymer aerogel having a thermalconductivity of less than or equal to 25 mW/m·K at temperatures below150° C. and an at least bimodal pore size distribution with a first modeof pores having an average pore size of less than or equal to 50 nm anda second mode of pores having an average pore size of greater than 50nm. In some embodiment, the step (b) gel precursor solution can furtherinclude a catalyst (e.g., calcium carbonate, sodium carbonate or both).The catalyst can include a calcium (Ca) salt and a sodium (Na) salt in aCa:Na weight ratio of 5:1 to 1:1, preferably 3:1 to 1:1. In someembodiments, the Ca/Na catalyst can catalyst the polymerization ofresorcinol and formaldehyde to form a resorcinol formaldehyde polymermatrix. In some embodiments, step (e) can include supercritical drying,subcritical drying, thermal drying, evaporative air drying, or anycombination thereof. In particular instances, the drying step (e) can beperformed with thermal drying or evaporative air drying without the useof supercritical or subcritical drying. In some preferred instances,step (e) can include evaporative air drying. A benefit of the dryingprocess of the present invention is that it does not requiresupercritical or subcritical drying to create the aerogel from a wet gelprecursor. In some embodiments, the solvent in the solution of step (d)is exchanged with a second solvent having a higher volatility than thefirst solvent. The formation of the polymer gel in step (d) can resultin the formation of polymer particles from polymers that are solubilizedin the solution. The polymer particles can have varying particle sizes(e.g., at least two, three, four, or more different sizes), which canresult in a gelled network comprised of different particle sizes.Removal of the liquid phase from the gelled network during drying step(e) results in a network of polymer particles with varying sizes withgas (e.g., air) present where the liquid used to be. These differentparticle sizes produce an aerogel network having a multi-modal (e.g.,bimodal or trimodal) pore size distribution, with the fibers presentwithin this polymer particle network.

The following includes definitions of various terms and phrases usedthroughout this specification.

The term “aerogel” refers to a class of materials that are generallyproduced by forming a gel, removing a mobile interstitial solvent phasefrom the pores, and then replacing it with a gas or gas-like material.By controlling the gel and evaporation system, density, shrinkage, andpore collapse can be minimized. In some embodiments, the aerogels of thepresent invention can have low bulk densities (about 0.25 g/cm³ or less,preferably about 0.01 to 0.5 g/cm³), high surface areas (generally fromabout 10 to 1,000 m²/g and higher, preferably about 50 to 1000 m²/g),high porosity (about 80% and greater, preferably greater than about85%), and/or relatively large pore volume (more than about 1.0 mL/g,preferably about 1.2 mL/g and higher).

“Fiber,” as used herein, refers to an elongated structure having anapproximately uniform diameter of at least 100 nm and up to 200 μm.

“Non-fibrous organic polymer matrix,” as used herein, refers to a gelmatrix comprised of organic polymers that are not organized into afiber. Such a matrix typically comprises polymer particles clusteredtogether and arranged in such a way as to define voids, or “pores,”within an aerogel.

The use of the words “a” or “an” when used in conjunction with the term“comprising” “including,” “containing,” or “having” in the claims and/orthe specification may mean “one,” but it is also consistent with themeaning of “one or more,’ “at least one,” and “one or more than one.”

The terms “about” or “approximately” are defined as being close to asunderstood by one of ordinary skill in the art. In one non-limitingembodiment, the terms are defined to be within 10%, preferably within5%, more preferably within 1%, and most preferably within 0.5%.

The use of the term “or” in the claims is used to mean “and/or” unlessexplicitly indicated to refer to alternatives only or the alternativesare mutually exclusive, although the disclosure supports a definitionthat refers to only alternatives and “and/or.”

As used in this specification and claim(s), the words “comprising” (andany form of comprising, such as “comprise” and “comprises”), “having”(and any form of having, such as “have” and “has”), “including” (and anyform of including, such as “includes” and “include”) or “containing”(and any form of containing, such as “contains” and “contain”) areinclusive or open-ended and do not exclude additional, unrecitedelements or method steps.

The fiber-reinforced organic polymer aerogel of the present inventioncan “comprise,” “consist essentially of,” or “consist of” particularingredients, components, compositions, etc., disclosed throughout thespecification. With respect to the transitional phase “consistingessentially of,” in one non-limiting aspect, a basic and novelcharacteristic of the fiber-reinforced organic polymer aerogel of thepresent invention is that it has at least bimodal pore size distributionwith a first mode of pores having an average pore size of less than orequal to 50 nm and a second mode of pores having an average pore size ofgreater than 50 nm.

Other objects, features and advantages of the present invention willbecome apparent from the following figures, detailed description, andexamples. It should be understood, however, that the figures, detaileddescription, and examples, while indicating specific embodiments of theinvention, are given by way of illustration only and are not meant to belimiting. Additionally, it is contemplated that changes andmodifications within the spirit and scope of the invention will becomeapparent to those skilled in the art from this detailed description. Infurther embodiments, features from specific embodiments may be combinedwith features from other embodiments. For example, features from oneembodiment may be combined with features from any of the otherembodiments. In further embodiments, additional features may be added tothe specific embodiments described herein.

BRIEF DESCRIPTION OF THE DRAWINGS

The following drawings form part of the present specification and areincluded to further demonstrate certain aspects of the presentinvention. The invention may be better understood by reference to one ormore of these drawings in combination with the detailed description ofthe specification embodiments presented herein.

FIGS. 1A-1C are cross-sectional illustrations of some aerogelembodiments disclosed herein.

FIG. 2 is an illustration of a process of making a fiber-reinforcedorganic polymer aerogel.

FIG. 3 shows a portion of the pore size distribution as measured by gasadsorption for fiber-reinforced resorcinol formaldehyde aerogels withresorcinol to catalyst ratio (R/C) values of 300, 400, or 500.

FIG. 4 shows a portion of the pore size distribution as measured bymercury intrusion porosimetry for a fiber-reinforced resorcinolformaldehyde aerogel with an R/C value of 300.

FIG. 5 shows a portion of the pore size distribution as measured bymercury intrusion porosimetry for a fiber-reinforced resorcinolformaldehyde aerogel with an R/C value of 400.

FIG. 6 shows a portion of the pore size distribution as measured bymercury intrusion porosimetry for a fiber-reinforced resorcinolformaldehyde aerogel with an R/C value of 500.

FIG. 7 shows the pore size distribution of the PET fiber-reinforcedmixed catalyst resorcinol formaldehyde aerogel materials of the presentinvention at a catalyst mixture ratio of 1(Ca):1(Na), R/C 600, and 25%and 30% solids as measured by mercury intrusion porosimetry.

FIG. 8 shows is a graph of the relationship between temperature andthermal conductivity for the vacuum insulated panels usingPET-reinforced mixed-catalyst resorcinol formaldehyde aerogel blanketsof the present invention.

FIG. 9 shows is a graph of the relationship between number of repeatedwrappings and weight change a PET-reinforced mixed-catalyst resorcinolformaldehyde aerogel blanket of the present invention a commercialsilica gel aerogel blanket.

While the invention is susceptible to various modifications andalternative forms, specific embodiments thereof are shown by way ofexample in the drawings and may herein be described in detail. Thedrawings may not be to scale.

DETAILED DESCRIPTION

A discovery has been made that provides a fiber-reinforced organicpolymer aerogel with superior thermal and mechanical properties ascompared to unreinforced aerogels. Without wishing to be bound bytheory, it is believed that the presence of the multi-modal (e.g.,bimodal or trimodal) pore size distribution throughout the aerogelnetwork contributes to the low thermal conductivity (e.g., ≤25 mW/m·K ata temperature below 150° C.) of the aerogels of the present invention.The presence of the fibers is believed to contribute to the mechanicalstrength of the aerogels and influence aerogel pore structures. Thepresence of different polymer particle sizes in the wet-gel and fibermatrix is believed to prevent network collapse during drying, whichallows the aerogels of the present invention to be produced by processessuch as thermal drying or evaporative air drying in lieu of, or inaddition to, the more commonly used freeze-drying and super-criticaldrying processes.

These and other non-limiting aspects of the present invention areprovided in the following subsections.

A. Fiber-Reinforced Organic Polymer Aerogels

The fiber-reinforced organic polymer aerogels of the present inventioninclude a non-fibrous organic polymer matrix and fibers comprised in thenon-fibrous organic polymer matrix. FIGS. 1A, 1, and 1C providenon-limiting illustrations of aerogel 2 of the present invention, inwhich fiber matrix 4 is embedded. In FIG. 1A, fiber matrix 4 isdistributed throughout aerogel 2; that is, the fiber matrix has the samesize and volume as the aerogel itself. FIGS. 1B and 1C illustrateembodiments in which fiber matrix 4 is not distributed throughoutaerogel 2, but is instead limited to a portion of the aerogel. Fibermatrix 4 can be located in various locations within aerogel 2, asillustrated by the differing locations in FIG. 1B, where fiber matrix 4is located centrally within the aerogel, and FIG. 1C, where the fibermatrix is located in a bottom portion of the aerogel.

1. Organic Polymer Matrix

The organic polymer matrix of the present invention can be composed of avariety of organic polymers. In a preferred embodiment, the reinforcedaerogel matrix is made from resorcinol formaldehyde or polyimide. Theorganic components can include thermoplastic or thermoset polymers,co-polymers thereof, and blends thereof that are discussed throughoutthe present application. The polymers can be branched, linear, orcross-linked. The fiber-reinforced polymer aerogel can include polymersor polymer precursors of polyethylene terephthalate (PET), apolycarbonate (PC) family of polymers, polybutyrate adipateterephthalate (PBAT), a biodegradable random copolymer, specifically acopolyester of adipic acid, 1,4-butanediol and dimethyl terephthalate),poly(1,4-cyclohexylidene cyclohexane-1,4-dicarboxylate) (PCCD), glycolmodified polycyclohexyl terephthalate (PCTG), poly(phenylene oxide)(PPO), polyvinyl chloride (PVC), polystyrene (PS),polymethylmethacrylate (PMMA), polyacrylic acid, poly(methacrylic)acid,polyethyleneimine, polyetherimide (PEI) and their derivatives,thermoplastic elastomer (TPE), terephthalic acid (TPA) elastomers,poly(cyclohexanedimethylene terephthalate) (PCT), polyethylenenaphthalate (PEN), polyamide (PA), polysulfone sulfonate (PSS),sulfonates of polysulfones, polyether ether ketone (PEEK), polyetherketone ketone (PEKK), acrylonitrile butyldiene styrene (ABS),polyphenylene sulfide (PPS), unsaturated polyester resins, polyurethane(PU), polyoxybenzylmethylenglycolanhydride (e.g., bakelite),urea-formaldehyde, diallyl-phthalate, epoxy resin, epoxy vinylesters,cyanate esters of polycyanurates, dicyclopentadiene, phenolics,benzoxazines, polyacrylate, polyacrylonitrile, polyurea, polyamine,polyimide, polyether, polyester, polyvinyl alcohol (PVOH), polyvinylbutyral (PVB), polyfurfural alcohol, polyphenol, phenol furfurylalcohol, melamine formaldehyde, resorcinol formaldehyde, cresolformaldehyde, phenol formaldehyde, polyvinyl alcohol dialdehyde,polycyanurate, polyacrylamide, various epoxies, agar, agarose,co-polymers thereof, or blends thereof. For this purpose of thisdisclosure PVOH and PVB can be derived from vinyl acetate which isderived from acetaldehyde are not considered polyolefins. In particularembodiments, the reinforced polymer aerogels include an organic polymermatrix of a polymer selected from a polyamine, a polyamide, a polyimide,a poly(amide-imide), a poly(amic amide), a poly(ether imide), apolyphenol, a polyvinyl alcohol, a polyvinyl butyral, a polyurethane, apolyurea, a polyether, a polyester, a polyacid, a polycarbonate, or anycombination thereof. The polymer can be included in a composition thatincludes said polymer and additives. Non-limiting examples of additivesinclude coupling agents, antioxidants, heat stabilizers, flow modifiers,colorants, opacifiers, surfactants, etc., or any combinations thereof.

The characteristics or properties of the final polymer are significantlyimpacted by the choice of precursor monomers, which are used to producethe polymer. Factors to be considered when selecting monomers includethe properties of the final polymer, such as the thermal conductivity,mechanical properties, flexibility, thermal stability, coefficient ofthermal expansion (CTE), coefficient of hydroscopic expansion (CHE) andany other properties specifically desired, as well as cost. Often,certain important properties of a polymer for a particular use can beidentified. Other properties of the polymer may be less significant, ormay have a wide range of acceptable values; so many different monomercombinations could be used.

Other factors to be considered in the selection of precursor monomers(e.g., resorcinol and formaldehyde) include the expense and availabilityof the monomers chosen. Commercially available monomers that areproduced in large quantities generally decrease the cost of producingpolymer materials since such monomers are in general less expensive thanmonomers produced on a lab scale and pilot scale. Additionally, the useof high purity commercially available monomers can improve the overallreaction efficiency because additional reactions are not required toproduce a monomer, which is then incorporated into the polymer. Apotential supplier of precursor monomers includes Sigma-Aldrich, USA.

In some embodiments, the backbone of the polymer includes reactivesubstituents. The substituents (e.g., chain end groups, oligomers,functional groups, etc.) can be directly bonded to the backbone, linkedto the backbone through a linking group (e.g., a tether or a flexibletether), or brought about by further reaction of polymer backbone. Forexample, partial hydrolysis of polyester or polycarbonate polymer canrelease functional groups that can be used in reinforcing. Any furtherchemical or physical modification of the polymer backbone for thispurpose is contemplated herein. In preferred aspects, the polymerprecursor includes a reinforceable functional group selected from amine,amide, imide, ether, phenol, alcohol, butyral, urethane, urea,carbonate, ester, ether, or acid, or any combination thereof. In otherembodiments, a compound or particles can be incorporated (e.g., blendedand/or encapsulated) into the polymer structure without being covalentlybound. In some instances, the incorporation of the compound or particlescan be performed during polymerization. In some instances, particles canaggregate, thereby producing polymers having domains with differentconcentrations of the non-covalently bound compounds or particles.

In some instances, the polymer precursor compositions used to preparethe fiber-reinforced polymer aerogel of the present invention caninclude multifunctional monomers with at least three reactivefunctionalities. The multifunctional monomers can be a substituted orunsubstituted aliphatic multifunctional amine, a substituted orunsubstituted aromatic multifunctional amine, or a multifunctional aminethat includes a combination of an aliphatic and two aromatic groups, ora combination of an aromatic and two aliphatic groups. A non-limitinglist of possible multifunctional amines include propane-1,2,3-triamine,2-aminomethylpropane-1,3-diamine, 3-(2-aminoethyl)pentane-1,5-diamine,bis(hexamethylene)triamine, N′,N′-bis(2-aminoethyl)ethane-1,2-diamine,N′,N′-bis(3-aminopropyl)propane-1,3-diamine,4-(3-aminopropyl)heptane-1,7-diamine,N′,N′-bis(6-aminohexyl)hexane-1,6-diamine, benzene-1,3,5-triamine,cyclohexane-1,3,5-triamine, melamine,N-2-dimethyl-1,2,3-propanetriamine, diethylenetriamine, 1-methyl or1-ethyl or 1-propyl or 1-benzyl-substituted diethylenetriamine,1,2-dibenzyldiethylenetriamine, lauryldiethylenetriamine,N-(2-hydroxypropyl)diethylenetriamine,N,N-bis(1-methylheptyl)-N-2-dimethyl-1,2,3-propanetriamine,2,4,6-tris(4-(4-aminophenoxy)phenyl)pyridine,N,N-dibutyl-N-2-dimethyl-1,2,3-propanetriamine,4,4′-(2-(4-aminobenzyl)propane-1,3-diyl)dianiline,4-((bis(4-aminobenzyl)amino)methyl)aniline,4-(2-(bis(4-aminophenethyl)amino)ethyl)aniline,4,4′-(3-(4-aminophenethyl)pentane-1,5-diyl)dianiline,1,3,5-tris(4-aminophenoxy)benzene, 4,4′,4″-methanetriyltrianiline,N,N,N′,N′-tetrakis(4-aminophenyl)-1,4-phenylenediamine, apolyoxypropylenetriamine, octa(aminophenyl)polyhedral oligomericsilsesquioxane, or combinations thereof. A specific example of apolyoxypropylenetriamine is JEFFAMINE® T-403 from Huntsman Corporation,The Woodlands, Tex. USA. The multifunctional monomers can also includealcohols, acids, esters, anhydrides, acid chlorides, etc. Suitablemultifunctional monomers include, but are not limited to,multifunctional alcohols such as 2-methyl-1,3-propanediol,1,2-propanediol, 1,3-propanediol, glycerol, and ethylene glycol,arabitol, erythritol, glycerol, isomalt, lactitol, maltitol, mannitol,sorbitol, xylitol, sucrose, sucralose, benzene-1,3,5-triol,cyclohexane-1,2,4-triol; multifunctional acids such as1,3,5-cyclohexanetricarboxylic acid, Kemp's triacid,1,2,3-benzenetricarboxylic acid, 1,2,4-benzenetricarboxylic acid,1,3,5-benzenetricarboxylic acid,5-(4-carboxy-2-nitrophenoxy)-isophthalic acid,1,2,3,4-butanetetracarboxylic acid,tetrahydrofuran-2,3,4,5-tetracarboxylic acid,2,2′,2″,2′″-[1,2-ethanediylidene-tetrakis(thio)]-tetrakisacetic acid,cyclobutanetetracarboxylic acid, 1,2,4,5-benzenetetracarboxylic acid,mellitic acid, 1,4,5,8-naphthalene tetracarboxylic acid, and1,2,3,4,5,6-cyclohexanehexacarboxylic acid; multifunctional esters suchas methyl, ethyl or butyl esters of the above acids andtriethylmethanetricarboxylate, triethyl 1,1,2-ethanetricarboxylate,tetraethyl 1,1,2,2-ethanetetracarboxylate, tetraethylethylenetetracarboxylate, tetramethylexo,exo-tetracycloundeca-3,8-diene-3,4,8,9-tetracarboxylate, andpentamethyl cyclopentadiene-1,2,3,4,5-pentacarboxylate; anhydrides suchas 1,2,4-benzenetricarboxylic anhydride, 1,2,4,5-benzenetetracarboxylicdianhydride, and bicyclo[2,2,2]oct-7-ene-2,3,5,6-tetracarboxylicanhydride; and acid chlorides such as 1,3,5-benzenetricarbonyl chloride.In some embodiments, the polymer matrix is a resorcinol formaldehydepolymer.

Polymer matrices made from multifunctional monomers can be strengthenedby cross-linking. Methods of cross-linking polymers are known in theart, as in, for example, U.S. Pat. No. 8,637,582 to Gawryla & Schiraldiand U.S. Pat. No. 9,434,832 to Meador. In some embodiments, thecross-linked polymer matrix comprises a cross-linked resorcinolformaldehyde polymer.

2. Fiber Reinforcement

Embodiments of the aerogels disclosed herein are internally reinforcedby fibers. The fibers can be composed of a variety of materials. Asnon-limiting examples, the fibers can be glass fibers, polyester fibers,carbon fibers, aramid fibers, polyethylene fibers, polyamide fibers,basalt fibers, steel fibers, cellulose fibers, ceramic fibers, or acombination thereof.

The fibers can be arranged in a variety of fibrous structures. Forexample, the fibers can form a fiber matrix, as in felt, batting, loftybatting, a mat, a woven fabric, a non-woven fabric. The fiber-reinforcedaerogel can comprise any of these fibrous materials alone or incombination. The fibers within the aerogel can be unidirectionally oromnidirectionally oriented. In some embodiments, the fibers can have anaverage filament cross sectional area from 5 μm² to 40,000 μm². Thefibers can have an average length of 20 mm to 100 mm.

In some embodiments, the fibers in the fiber-reinforced aerogel aredistributed throughout the aerogel. In such embodiments, the cast gelhas the same shape and volume as the fibrous material comprised withinthe gel. Such embodiments can be formed during the casting process byadding the appropriate amount of liquid gel precursor to just submerge afibrous material. In some embodiments, a layered aerogel product can beformed in which a portion of the aerogel is free of fibers.

3. Pore Size Distribution

In embodiments disclosed herein, fiber-reinforced aerogels arecharacterized by their pore size distribution. Pore size distributioncan be measured in a variety of ways known to those of ordinary skill inthe art, including, for example, nitrogen gas adsorption and mercuryintrusion porosimetry (MIP). In some embodiments, the pore sizedistribution is at least bimodal. In such embodiments, there are atleast two distinct groups, or “modes,” of pore diameters in the aerogel.For example, an aerogel with a bimodal distribution may have onepopulation of pores with an average diameter of 50 nm or less andanother population of pores with an average diameter of greater than 50nm, with no additional distinct groups of pores. Distinct modes of porescan often be visualized in a plot showing the pore size distribution,which can be a plot of pore volume or pore number versus pore diameter.In such plots, a mode can be visualized as a peak. In a multi-modal poresize distribution, more than one distinct peak can be seen. Someembodiments may have 2, 3, 4, 5, or more distinct modes. An embodimentwith at least three distinct modes of pores is described herein ashaving an at least trimodal pore size distribution.

The pore size distribution can be affected during the manufacturingprocess by the relative concentration of a basic compound, such ascalcium carbonate, present in a gel precursor solution. For example,decreasing the molar ratio of base in the gel precursor solution canincrease the population of pores having relatively large diameters(e.g., greater than 10 μm), leading to the creation of one or morelarge-diameter modes.

4. Tensile Strength

In some embodiments described herein, the fiber-reinforced organicpolymer aerogels are characterized by their tensile strength, which isalso known as ultimate tensile strength (UTS). This is a measure of thecapacity of a material to withstand loads tending to elongate. Thetensile strength of embodiments described herein are significantlygreater than that of previously available fiber-reinforced aerogels. Asused herein, the tensile strength is the ultimate tensile strength asmeasured according to American Standard Testing Method (ASTM) D5034Standard Specification for Breaking Force and Elongation of TextileFabrics (Grab Method). The tensile strength may vary depending on thedirection in which the test is performed. For some embodiments of theaerogels described herein, the tensile strength is greater when measuredin the machine direction than when measured in the cross direction.

B. Synthesis of Fiber-Reinforced Organic Polymer Aerogels

Aerogels of the present disclosure can be made using a multi-stepprocess that includes 1) preparation of the fiber-reinforced organicpolymer gel, 2) solvent exchange and 3) drying of the fiber-reinforcedgel to form the aerogel. FIG. 2 illustrates an exemplary method ofmaking fiber-reinforced organic polymer aerogel 2. In step 1, fibrousmaterial 4 can be placed inside a casting container 10. In step 2, gelprecursor solution 11 including organic polymer precursors and optionalcatalyst can be prepared and poured into the casting container 10,submerging fibrous material 4. In step 3, submerged fibrous material 4can be gelled and dried to produce fiber-reinforced organic polymeraerogel 2. These process steps are discussed in more detail below.

1. Preparation of the Fiber-Reinforced Organic Polymer Gel

The first stage in the synthesis of a fiber-reinforced organic polymeraerogel is the synthesis of a fiber-reinforced organic polymer wet gel.To create the wet gel, a gel precursor solution is combined with fibers,followed by gelation. This can be accomplished by, for example, pouringthe solution over fibers that have been placed in a casting container oron a casting sheet, causing the fibers to become immersed in thesolution. Additionally or alternatively, fibers can be stirred into orotherwise combined with the gel precursor solution before or aftercasting. Gelation causes the creation of a fiber-reinforced wet gel.

Generally, organic polymer gels are prepared from organic monomers bypolymerization, such as step-growth polymerization, chain-growthpolymerization, or photopolymerization. For example, if a polyamideaerogel is desired, at least one diacid monomer can be reacted with atleast one diamino monomer in a reaction solvent by condensation in astep-growth polymerization to form a polyamide. As discussed above, anumber of other polymers, co-polymers thereof, or blends thereof can beused in the fiber-reinforced polymer aerogels disclosed herein. In someinstances, the polymer matrix comprises a polyimide matrix. If apolyimide aerogel is desired, at least one acid monomer can be reactedwith at least one diamino monomer in a reaction solvent to form apoly(amic acid). Numerous acid monomers and diamino monomers may be usedto synthesize the poly(amic acid). In one aspect, the poly(amic acid) iscontacted with an imidization catalyst in the presence of a chemicaldehydrating agent to form a polymerized polyimide gel via an imidizationreaction. Any imidization catalyst suitable for driving the conversionof polyimide precursor to the polyimide state is suitable. Preferredchemical imidization catalysts comprise at least one compound selectedfrom the group consisting of pyridine, methylpyridines, quinoline,isoquinoline, 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU),triethylenediamine, lutidine, N-methylmorpholine, triethylamine,tripropylamine, tributylamine, imidazole or a substituted imidazole, atriazole or a substituted triazole, a tetrazole or substitutedtetrazole, a purine or a substituted purine, a pyrazole or a substitutedpyrazole, other trialkylamines, or combinations thereof. Any dehydratingagent suitable for use in formation of an imide ring from an amic acidprecursor is suitable. Preferred dehydrating agents comprise at leastone compound selected from the group consisting of acetic anhydride,propionic anhydride, n-butyric anhydride, benzoic anhydride,trifluoroacetic anhydride, oxalyl chloride, thionyl chloride, phosphorustrichloride, dicyclohexylcarbodiimide, 1,1′-carbonyldiimidazole (CDI),di-tert-butyl dicarbonate (Boc₂O), or combinations thereof.

In some embodiments, the polymer matrix comprises a resorcinolformaldehyde polymer. To prepare a gel comprising this polymer,resorcinol and formaldehyde can be combined together in aqueous solutionin the presence of a metal salt catalyst. The resorcinol andformaldehyde can combine to form the resorcinol formaldehyde polymerparticles, which form the gel matrix. The resorcinol to formaldehyde(R/F) ratio can be any desired ratio to form the desired resorcinolformaldehyde polymer. By way of example, the R/F ratio can be 5:1 to0.25:1, or greater than, equal to, or between any two of 5:1, 4:1, 3:1,2:1, 1:1, 0.5:1, and 0.25:1. In one instance, the R/F ratio is 0.6:1 to0.4:1, or about 0.5:1. Non-limiting examples of metal salts can includelithium carbonate (Li₂CO₃), sodium carbonate (Na₂CO₃), potassiumcarbonate (K₂CO₃), rubidium carbonate (Rb₂CO₃), cesium carbonate(Cs₂CO₃), magnesium carbonate (MgCO₃), calcium carbonate (CaCO₃),strontium carbonate (SrCO₃), barium carbonate (BaCO₃), or combinationsthereof. In some embodiments, the catalyst can include calcium andsodium in a weight ratio of 5:1 to 1:1, or equal to, or between any twoof 5:1, 4:1, 3:1, 2:1, and 1:1. A molar ratio of resorcinol to catalyst(R/C) ratio can be greater than, equal to, or between any two of 1:1,10:1, 20:1, 30:1, 40:1, 50:1, 100:1, 200:1, 300:1, 400:1, 500:1, 600:1,700:1, 800:1, 900:1, 1000:1, 1500:1, and 2000:1. The total solidscontent in the gel precursors (i.e., resorcinol, formaldehyde, andcatalyst) can be at least, equal two or between any two of 15% w/v, 20%w/v, 25% w/v, 30% w/v, 35% w/v, 40% w/v and 50% w/v.

The reaction solvent for polymerization, cross-linking, or both can beamide solvents such as but not limited to formamide, N-methylformamide,N,N-dimethylformamide, N,N-diethylformamide, N,N-dimethylacetamide,N,N-diethylacetamide, 2-pyrrolidone, N-methyl-2-pyrrolidone,1-methyl-2-pyrrolidinone, N-cyclohexyl-2-pyrrolidone, N-vinylacetamide,N-vinylpyrrolidone, hexamethylphosphoramide, and1,13-dimethyl-2-imidazolidinone; organosulfur solvents such as but notlimited to dimethylsulfoxide, diethylsulfoxide, diethyl sulfoxide,methylsulfonylmethane, and sulfolane; ether solvents including but notlimited to cyclopentyl methyl ether, di-tert-butyl ether, diethyl ether,diethylene glycol diethyl ether, diglyme, diisopropyl ether,dimethoxyethane, dimethoxymethane, 1,4-dioxane, ethyl tert-butyl ether,glycol ethers, methoxyethane, 2-(2-methoxyethoxy)ethanol, methyltert-butyl ether, 2-methyltetrahydrofuran, morpholine, tetraglyme,tetrahydrofuran, tetrahydropyran, and triglyme; hydrocarbon solventsincluding but not limited to benzene, cycloheptane, cyclohexane,cyclohexene, cyclooctane, cyclopentane, decalin, dodecane, durene,heptane, hexane, limonene, mesitylene, methylcyclohexane, naphtha,octadecene, pentamethylbenzene, pentane, pentanes, petroleum benzene,petroleum ether, toluene tridecane, turpentine, and xylene; nitrosolvents including but not limited to nitrobenzene, nitroethane, andnitromethane; alcohol solvents including but not limited to methanol,ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, isobutanol,tert-butanol, 3-methyl-2-butanol, 3,3-dimethyl-2-butanol, 2-pentanol,3-pentanol, 2,2-dimethylpropan-1-ol, cyclohexanol, diethylene glycol,tert-amyl alcohol, phenols, cresols, xylenols, catechol, benzyl alcohol,1,4-butanediol, 1,2,4-butanetriol, butanol, 2-butanol, N-butanol,tert-butyl alcohol, diethylene glycol, ethylene glycol, 2-ethylhexanol,furfuryl alcohol, glycerol, 2-(2-methoxyethoxy)ethanol,2-methyl-1-butanol, 2-methyl-1-pentanol, 3-methyl-2-butanol, neopentylalcohol, 2-pentanol, 1,3-propanediol, and propylene glycolcycol; ketonesolvents including but not limited to hexanone, acetone, methyl ethylketone, methyl isobutyl ketone, disobutyl ketone, acetophenone,butanone, cyclopentanone, ethyl isopropyl ketone, 2-hexanone,isophorone, mesityl oxide, methyl isopropyl ketone,3-methyl-2-pentanone, 2-pentanone, and 3-pentanoneacetyl acetone;halogenated solvents including but not limited to benzotrichloride,bromoform, bromomethane, carbon tetrachloride, chlorobenzene,1,2-dichlorobenzene, 1,3-dichlorobenzene, 1,4-dichlorobenzene,chlorofluorocarbon, chloroform, chloromethane,1,1-dichloro-1-fluoroethane, 1,1-dichloroethane, 1,2-dichloroethane,1,1-dichloroethene, 1,2-dichloroethene, dichloromethane, diiodomethane,FC-75, haloalkane, halomethane, hexachlorobutadiene,hexafluoro-2-propanol, parachlorobenzotrifluoride,perfluoro-1,3-dimethylcyclohexane, perfluorocyclohexane,perfluorodecalin, perfluorohexane, perfluoromethylcyclohexane,perfluoromethyldecalin, perfluorooctane, perfluorotoluene,perfluorotripentylamine, tetrabromomethane, 1,1,1,2-tetrachloroethane,1,1,2,2-tetrachloroethane, tetrachloroethylene, 1,1,1-tribromoethane,1,3,5-trichlorobenzene, 1,1,1-trichloroethane, 1,1,2-trichloroethane,trichloroethylene, 1,2,3-trichloropropane, 2,2,2-trifluoroethanol, andtrihalomethane; ester solvents including but not limited to methylacetate, ethyl acetate, butyl acetate, 2-methoxyethyl acetate, benzylbenzoate, bis(2-ethylhexyl) adipate, bis(2-ethylhexyl) phthalate,2-butoxyethanol acetate, sec-butyl acetate, tert-butyl acetate, diethylcarbonate, dioctyl terephthalate, ethyl acetate, ethyl acetoacetate,ethyl butyrate, ethyl lactate, ethylene carbonate, hexyl acetate,isoamyl acetate, isobutyl acetate, isopropyl acetate, methyl acetate,methyl lactate, methyl phenylacetate, methyl propionate, propyl acetate,propylene carbonate, and triacetin; water, or mixtures thereof. Thereaction solvent and other reactants can be selected based on thecompatibility with the materials and methods applied i.e., if thepolymerized gel is to be cast onto a support film, injected into amoldable part, or poured into a shape for further processing into a workpiece. The reaction solvent and other reactants will be selected basedon the compatibility with the fiber material.

In some aspects, an agent (e.g., curing agents, dehydration agents,radical initiators (photo or thermal) or the like) suitable for drivingthe conversion of the reactants (i.e., polymer precursor, polymers) tothe polymer matrix can be employed. The conversion may also be driven byheat or irradiation with electromagnetic radiation (e.g., infrared or UVradiation). Curing agents can be selected based on the types of polymersformed. Non-limiting examples of such compounds include pyridine,methylpyridines, quinoline, isoquinoline,1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), DBU phenol salts, carboxylicacid salts of DBU, triethylenediamine, carboxylic acid slats oftriethylenediamine, lutidine, N-methylmorpholine, triethylamine,tripropylamine, tributylamine, other trialkylamines, imidazole, 2-methylimidazole, 2-ethyl-4-methylimidazole, or combinations thereof.Dehydrating agents may include acetic anhydride, propionic anhydride,n-butyric anhydride, benzoic anhydride, trifluoroacetic anhydride,oxalyl chloride, thionyl chloride, phosphorus trichloride,dicyclohexylcarbodiimide, 1,1′-carbonyldiimidazole (CDI), di-tert-butyldicarbonate (Boc₂O), or combinations thereof. Radical initiators includeazobisisobutyronitrile (AIBN), benzoyl peroxide,2,2-dimethoxy-2-phenylacetophenone (DMPA) and the like, or combinationthereof.

Reaction conditions to effect polymerization can vary depending on thetype of polymer precursors used. Reaction conditions can includetemperature and pressure. Temperatures can range from at least, equalto, or between any two of 50° C., 75° C., 100° C., 125° C., 150° C.,175° C. and 200° C. at atmospheric pressure (about 0.101 MPa), orbetween 80° C. and 100° C. The gel precursor solution can be cast orpoured over the fiber source, and held until a gel forms (e.g., 1 minuteto 30 days). In some embodiments, the gel precursor solution can be heldfor 1 to 3 days to produce a fiber-reinforced resorcinol formaldehydepolymeric matrix.

2. Solvent Exchange

After the reinforced organic polymer wet gel is synthesized, it can bedesirable to conduct a solvent exchange wherein the reaction solventused in the gel precursor is exchanged for a second solvent moresuitable for the drying step. Accordingly, in one embodiment, a solventexchange can be conducted wherein the wet gel is placed inside of avessel and submerged in a mixture comprising the reaction solvent andthe second solvent. Then, a high-pressure atmosphere is created insideof the vessel thereby forcing the second solvent into the reinforcedpolymerized gel and displacing a portion of the reaction solvent.Alternatively, the solvent exchange step may be conducted without theuse of a high-pressure environment. It may be necessary to conduct aplurality of rounds of solvent exchange. The time necessary to conductthe solvent exchange will vary depending upon the type of polymerundergoing the exchange as well as the reaction solvent and secondsolvent being used. In one embodiment, each solvent exchange lastsapproximately twenty-four hours. In another embodiment, each solventexchange lasts approximately 30 minutes.

Exemplary second solvents include amide solvents such as but not limitedto formamide, N-methylformamide, N,N-dimethylformamide,N,N-diethylformamide, N,N-dimethylacetamide, N,N-diethylacetamide,2-pyrrolidone, N-methyl-2-pyrrolidone, 1-methyl-2-pyrrolidinone,N-cyclohexyl-2-pyrrolidone, N-vinylacetamide, N-vinylpyrrolidone,hexamethylphosphoramide, and 1,13-dimethyl-2-imidazolidinone;organosulfur solvents (e.g., dimethylsulfoxide, diethylsulfoxide,diethyl sulfoxide, methylsulfonylmethane, and sulfolane); ether solvents(e.g., cyclopentyl methyl ether, di-tert-butyl ether, diethyl ether,diethylene glycol diethyl ether, diglyme, diisopropyl ether,dimethoxyethane, dimethoxymethane, 1,4-dioxane, ethyl tert-butyl ether,glycol ethers, methoxyethane, 2-(2-methoxyethoxy)ethanol, methyltert-butyl ether, 2-methyltetrahydrofuran, morpholine, tetraglyme,tetrahydrofuran, tetrahydropyran, and triglyme); hydrocarbon solvents(e.g., benzene, cycloheptane, cyclohexane, cyclohexene, cyclooctane,cyclopentane, decalin, dodecane, durene, heptane, hexane, limonene,mesitylene, methylcyclohexane, naphtha, octadecene, pentamethylbenzene,pentane, pentanes, petroleum benzene, petroleum ether, toluenetridecane, turpentine, and xylene); nitro solvents (e.g., nitrobenzene,nitroethane, and nitromethane); alcohol solvents (e.g., methanol,ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, isobutanol,tert-butanol, 3-methyl-2-butanol, 3,3-dimethyl-2-butanol, 2-pentanol,3-pentanol, 2,2-dimethylpropan-1-ol, cyclohexanol, diethylene glycol,tert-amyl alcohol, phenols, cresols, xylenols, catechol, benzyl alcohol,1,4-butanediol, 1,2,4-butanetriol, butanol, 2-butanol, N-butanol,tert-butyl alcohol, diethylene glycol, ethylene glycol, 2-ethylhexanol,furfuryl alcohol, glycerol, 2-(2-methoxyethoxy)ethanol,2-methyl-1-butanol, 2-methyl-1-pentanol, 3-methyl-2-butanol, neopentylalcohol, 2-pentanol, 1,3-propanediol, and propylene glycolcycol); ketonesolvents (e.g., hexanone, acetone, methyl ethyl ketone, methyl isobutylketone, disobutyl ketone, acetophenone, butanone, cyclopentanone, ethylisopropyl ketone, 2-hexanone, isophorone, mesityl oxide, methylisopropyl ketone, 3-methyl-2-pentanone, 2-pentanone, and3-pentanoneacetyl acetone); halogenated solvents (e.g.,benzotrichloride, bromoform, bromomethane, carbon tetrachloride,chlorobenzene, 1,2-dichlorobenzene, 1,3-dichlorobenzene,1,4-dichlorobenzene, chlorofluorocarbon, chloroform, chloromethane,1,1-dichloro-1-fluoroethane, 1,1-dichloroethane, 1,2-dichloroethane,1,1-dichloroethene, 1,2-dichloroethene, dichloromethane, diiodomethane,FC-75, haloalkane, halomethane, hexachlorobutadiene,hexafluoro-2-propanol, parachlorobenzotrifluoride,perfluoro-1,3-dimethylcyclohexane, perfluorocyclohexane,perfluorodecalin, perfluorohexane, perfluoromethylcyclohexane,perfluoromethyldecalin, perfluorooctane, perfluorotoluene,perfluorotripentylamine, tetrabromomethane, 1,1,1,2-tetrachloroethane,1,1,2,2-tetrachloroethane, tetrachloroethylene, 1,1,1-tribromoethane,1,3,5-trichlorobenzene, 1,1,1-trichloroethane, 1,1,2-trichloroethane,trichloroethylene, 1,2,3-trichloropropane, 2,2,2-trifluoroethanol, andtrihalomethane); ester solvents (e.g., methyl acetate, ethyl acetate,butyl acetate, 2-methoxyethyl acetate, benzyl benzoate,bis(2-ethylhexyl) adipate, bis(2-ethylhexyl) phthalate, 2-butoxyethanolacetate, sec-butyl acetate, tert-butyl acetate, diethyl carbonate,dioctyl terephthalate, ethyl acetate, ethyl acetoacetate, ethylbutyrate, ethyl lactate, ethylene carbonate, hexyl acetate, isoamylacetate, isobutyl acetate, isopropyl acetate, methyl acetate, methyllactate, methyl phenylacetate, methyl propionate, propyl acetate,propylene carbonate, and triacetin); water, and mixtures thereof. Eachsecond solvent has a freezing point. For example tert-butyl alcohol hasa freezing point of 25.5 degrees Celsius and water has a freezing pointof 0 degrees Celsius under one atmosphere of pressure. Preferably, atleast one solvent exchange is performed with acetone.

The temperature and pressure used in the solvent exchange process may bevaried. The duration of the solvent exchange process can be adjusted byperforming the solvent exchange at a varying temperatures or atmosphericpressures, or both, provided that the pressure and temperature insidethe pressure vessel does not cause either the first solvent or thesecond solvent to leave the liquid phase and become gaseous phase, vaporphase, solid phase, or supercritical fluid. Generally, higher pressuresand/or temperatures decrease the amount of time required to perform thesolvent exchange, and lower temperatures and/or pressures increase theamount of time required to perform the solvent exchange.

3. Cooling and Drying

After the reinforced polymer gel has gone under solvent exchange, it isdesirable to conduct a drying step wherein the solvent within the gel isremoved. The drying step can be supercritical drying, subcriticaldrying, thermal drying, evaporative air-drying, or any combinationthereof. In one embodiment, the fiber-reinforced aerogel derived from apolymeric gel can be dried under ambient conditions, for example byremoving the solvent under a stream of air or anhydrous gas. In thisinstance the solvent in the gel is removed by evaporation and porecollapse is prevented by the reinforced matrix and the aerogel network.The drying may also be assisted by heating or irradiating withelectromagnetic radiation.

In another embodiment after solvent exchange, the polymerized reinforcedgel is exposed to subcritical drying. In this instance the gel is cooledbelow the freezing point of the second solvent and subjected to afreeze-drying or lyophilization process to produce the aerogel. Forexample, if the second solvent is water, then the polymerized gel iscooled to below 0° C. After cooling, the polymerized gel is subjected toa vacuum for a period of time wherein the second solvent is allowed tosublime.

In still another embodiment after solvent exchange, the polymerizedreinforced gel is exposed to subcritical drying with optional heatingafter the majority of the second solvent has been removed throughsublimation. In this instance the partially dried gel material is heatedto a temperature near or above the boiling point of the second solventfor a period of time. The period of time can range from a few hours toseveral days, although a typical period of time is approximately 4hours. During the sublimation process, a portion of the second solventpresent in the polymerized gel has been removed, leaving the aerogel.After solvent exchange, the gel can be dried at 80 to 100° C., or about85° C. under vacuum until dry (e.g., 0.5-3 days).

The final fiber-reinforced polymer aerogels can be any width or length.The fiber-reinforced aerogel can be in the form of defined geometry(e.g., a square or circular patch) or in the form of a sheet or roll. Insome instances, the internally reinforced aerogels can have a width upto 6 meters and a length of up to 10 meters, or from 0.01 to 6 meters,0.5 to 5 meters, 1 to 4 meters, or any range in between, and a length of1 to 10,000 meters, 5 to 1,000 meters, 10 to 100 meters or any rangethere between. The width of the composite can be 0.01, 0.05, 0.10, 0.15,0.20, 0.25, 0.30, 0.35, 0.40, 0.45, 0.50, 0.55, 0.60, 0.65, 0.70, 0.75,0.80, 0.85, 0.90, 0.95, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0,5.5, 6.0 feet or meters, including any value there between. The lengthof the internally reinforced aerogels can be 1, 10, 100, 500, 1000,1500, 2000, 2500, 3000, 3500, 4000, 4500, 5000, 5500, 6000, 6500, 7000,7500, 8000, 8500, 9000, 9500, 10000 meters or feet and include any valuethere between. In certain aspects, the length of the reinforced aerogelcan be 1000 feet or meters, and 60 inches or 1.5 meters, respectively,in width. In a further embodiment the internally reinforced aerogel is100 feet in length and 40 inches wide.

C. Articles of Manufacture

The fiber-reinforced organic polymer aerogels of the present inventioncan be included in an article of manufacture. For example, an article ofmanufacture can include a fiber-reinforced organic polymer matrix of apolymer selected from a polyamine, a polyamide, a polyimide, apoly(amide-imide), a poly(amic amide), a poly(ether imide), apolyphenol, a polyvinyl alcohol, a polyvinyl butyral, a polyurethane, apolyurea, a polyether, a polyester, a polyacid, a polycarbonate,resorcinol formaldehyde, or any combination thereof. In someembodiments, the article of manufacture is a thin film, monolith, wafer,blanket, core composite material, substrate for radiofrequency antenna,a sunscreen, a sunshield, a radome, insulating material for oil and/orgas pipeline, insulating material for liquefied natural gas pipeline,insulating material for cryogenic fluid transfer pipeline, insulatingmaterial for apparel, insulating material for aerospace applications,insulating material for buildings, cars, and other human habitats,insulating material for automotive applications, insulation forradiators, insulation for ducting and ventilation, insulation for airconditioning, insulation for heating and refrigeration and mobile airconditioning units, insulation for coolers, insulation for packaging,insulation for consumer goods, vibration dampening, wire and cableinsulation, insulation for medical devices, support for catalysts,support for drugs, pharmaceuticals, and/or drug delivery systems,aqueous filtration apparatus, oil-based filtration apparatus, andsolvent-based filtration apparatus.

In some embodiments, the fiber-reinforced organic polymer aerogel is inthe form of a blanket aerogel. Blanket aerogels are flexible,conformable aerogels that can be used to cover surfaces, including thosehaving a complex geometry. Aerogel blankets made from fiber-reinforcedaerogels described herein can be used in a variety of ways, including asinsulation for piping or for other structures having irregular surfaces.

EXAMPLES

The present invention will be described in greater detail by way ofspecific examples. The following examples are offered for illustrativepurposes only, and are not intended to limit the invention in anymanner. Those of skill in the art will readily recognize a variety ofnoncritical parameters which can be changed or modified to yieldessentially the same results.

Example 1 Single Layer Polyester Fiber-Reinforced ResorcinolFormaldehyde Aerogels

Fiber-reinforced resorcinol formaldehyde aerogels were produced in whichthe molar ratio of resorcinol to catalyst (R/C) in the gel precursor was100, 200, 300, 400, or 500. The catalyst was calcium carbonate. Thetotal solids content in the gel precursors (i.e., resorcinol,formaldehyde, and carbonate) was kept constant at 30% w/v. The molarratio of resorcinol to formaldehyde (R/F) was fixed at 0.5.

For a chosen R/C ratio, the required resorcinol was placed in a sealablereactor with 50 mL of deionized water and mechanically stirred untilcompletely dissolved. The calcium carbonate was added to the resorcinolsolution with continued stirring until completely dissolved. Therequired volume of 37 wt. % formaldehyde solution and additionaldeionized water to give the total volume of 600 mL at 30% solids wasadded to the reactor, which was sealed and stirred for 30 min. This gelprecursor solution was then poured over a 0.5 cm thick polyester fibermat laid in a casting container until the fiber mat was submerged. Thepolyester mat, trade name AB10, procured from Cytec Process Materials inHeanor, Derbyshire, UK is comprised of needle-punched polyester fibers,average fiber length of 64 mm and average fiber diameter of 180 μm. Thecast gel precursor was held at about 85° C. for three days to gel. Afterthree days, the fiber-reinforced wet gel was removed from the castingcontainer and submerged in acetone for 3 days at room temperature, withacetone exchanges every 12 hours. After solvent exchange, the gel wasdried by 85° C. for 2 days under vacuum.

The specific surface area, pore volume, and average pore diameter (“poresize” in Table 1) of the resulting fiber-reinforced aerogel blanketswere measured by gas adsorption, and the pore volume, density, andporosity were measured by mercury intrusion porosimetry (MIP). Thethermal conductivity was measured at a mean temperature of 20° C. and13.8 kPa pressure with a heat flow meter (HFM). Table 1 lists theproperties of polyester fiber-reinforced resorcinol formaldehyde aerogelblankets with the indicated R/C value and a solids content of 30% w/v.

TABLE 1 HFM Gas absorption Thermal MIP Specific conduc- Pore Pore Poresurface tivity Porosity volume Density volume size area (mW/m · R/C (%)(cm³/g) (g/cm³) (cm³/g) (nm) (m²/g) K) 100 45.4 1.38 0.328 1.14 22.4280.9 28.5 200 53.2 1.60 0.333 0.69 16.8 244.6 26.5 300 61.8 2.78 0.2220.54 17.0 186.0 24.3 400 76.3 3.24 0.235 0.34 14.6 115.8 23.5 500 65.93.28 0.201 0.27 11.9 133.1 24.2

The pore size distribution of the R/C 300, 400, and 500 samples asmeasured by gas adsorption is set forth in FIG. 3. The pore sizedistribution of the R/C 300, 400, and 500 samples as measured by mercuryintrusion porosimetry (MIP) are presented in FIG. 4, FIG. 5, and FIG. 6.MIP is able to measure pore diameters larger than 100 nm. FIGS. 4-6 showmulti-modal pore size distributions, with substantial populations ofpores larger than 100 nm.

Example 2 Multi-Layer Polyester Fiber-Reinforced Resorcinol FormaldehydeAerogels

Fiber-reinforced resorcinol formaldehyde aerogels were produced in whichthe molar ratio of resorcinol to catalyst ratio (R/C) in the gelprecursor was 300, 400, or 500. The catalyst was calcium carbonate. Thetotal solids content in the gel precursors (i.e., resorcinol,formaldehyde, and carbonate) was 20-30% w/v. The molar ratio ofresorcinol to formaldehyde (R/F) was fixed at 0.5.

For a chosen R/C ratio, the required resorcinol was placed in a sealablereactor with 50 mL of deionized water and mechanically stirred untilcompletely dissolved. The calcium carbonate was added to the resorcinolsolution with continued stirring until completely dissolved. Therequired volume of 37 wt. % formaldehyde solution and additionaldeionized water to give the total volume of 600 mL at 20-30% solidsdepending on the formulation, was added to the reactor, which was sealedand stirred for 30 min. This gel precursor solution was then poured overa 1 cm or 1.5 cm thick polyester fiber mat laid in a casting containeruntil the fiber mat was submerged. The mat consists of multi-layers ofsingle layer mat described in Example 1 and can be built to specifiedthickness. The layers can be bonded by the gel or needle-punched priorto incorporation of the gel to enhance bonding. The cast gel precursorwas held at about 85° C. for three days to gel. After three days, thefiber-reinforced wet gel was removed from the casting container andsubmerged in acetone for 3 days at room temperature, with acetoneexchanges every 12 hours. After solvent exchange, the gel was dried by85° C. for 2 days under vacuum.

The thermal conductivity was measured at a mean temperature of 20° C.and 13.8 kPa with a heat flow meter (HFM). Table 2 lists the propertiesof multi-layer polyester fiber-reinforced resorcinol formaldehydeaerogel blankets, with the indicated R/C value.

TABLE 2 No. of Thickness Solid content HFM Thermal conductivity Layers(mm) (%) (mW/m · K) 2 10 20 28.5 2 10 30 26.6 3 15 35 27.9 3 15 30 25.8

Example 3 Polyester Fiber-Reinforced Resorcinol Formaldehyde AerogelBlankets of the Present Invention

Fiber-reinforced resorcinol formaldehyde aerogels were produced in whichthe molar ratio of resorcinol to catalyst (R/C) in the gel precursor was400. The catalyst was calcium carbonate. The total solids content in thegel precursors (i.e., resorcinol, formaldehyde, and carbonate) was 30%w/v. The molar ratio of resorcinol to formaldehyde (R/F) was fixed at0.5.

The required resorcinol was placed in a sealable reactor with 50 mL ofdeionized water and mechanically stirred until completely dissolved. Thecalcium carbonate was added to the resorcinol solution with continuedstirring until completely dissolved. The required volume of 37 wt. %formaldehyde solution and additional deionized water to give the totalvolume of 600 mL at 30% solids was added to the reactor, which wassealed and stirred for 30 min. This gel precursor solution was thenpoured over a 1 cm thick polyester fiber mat laid in a casting containeruntil the fiber mat was submerged. A mat was procured from NonwovenInnovation & Research Institute in Leeds, UK and was comprised ofneedle-punched polyester fiber, average fiber length of 28 mm andaverage fiber diameter of 17 μm. The cast gel precursor was held atabout 85° C. for three days to gel. After this period, thefiber-reinforced wet gel was removed from the casting container andsubmerged in acetone for 3 days at room temperature, with acetoneexchanges every 12 hours. After solvent exchange, the gel was dried by85° C. for 2 days under vacuum.

The thermal conductivity was measured at a mean temperature of 20° C.and 13.8 kPa by heat flow meter (HFM). The ultimate tensile strength(UTS) and modulus were measured at 23° C. in the machine direction(“machine” in Table 3) and the cross direction (“cross” in Table 3)according to American Standard Testing Method (ASTM) ASTM D5034 StandardSpecification for Breaking Force and Elongation of Textile Fabrics (GrabMethod). The properties of polyester fiber reinforced resorcinolformaldehyde aerogel blankets of the present invention are set forth inTable 3. For comparison, Table 3 also includes the tensile testingvalues measured for a commercially available fiber-reinforced silicaaerogel blanket sold under the trade name Spaceloft® by Aspen Aerogel.As can be seen from Table 3, the tensile properties of the polyesterfiber-reinforced resorcinol formaldehyde aerogel of the presentinvention produced according to this Example 3 are many fold higher thanthose of the commercially available aerogel blanket.

TABLE 3 Thermal Machine Machine Cross Cross Cond. UTS Modulus UTSModulus (mW/m · K) (MPa) (MPa) (MPa) (MPa) Example 3 26 4.9 57.9 2.141.8 Comparative 16 0.4 15.6 0.1 6.1 Aerogel Blanket

Example 4 Glass Fiber-Reinforced Resorcinol Formaldehyde Aerogels

Fiber-reinforced resorcinol formaldehyde aerogels were produced in whichthe molar ratio of resorcinol to catalyst (R/C) in the gel precursor was100 or 400. The catalyst was calcium carbonate. The total solids contentin the gel precursors (i.e., resorcinol, formaldehyde, and carbonate)was kept constant 30% w/v. The molar ratio of resorcinol to formaldehyde(R/F) was fixed at 0.5.

For a chosen R/C ratio, the required resorcinol was placed in a sealablereactor with 50 mL of deionized water and mechanically stirred untilcompletely dissolved. The calcium carbonate was added to the resorcinolsolution with continued stirring until completely dissolved. Therequired volume of 37 wt. % formaldehyde solution and additionaldeionized water to give the total volume of 600 mL at 30% solids wasadded to the reactor, which was sealed and stirred for 30 min. This gelprecursor solution was then poured over a 1 cm thick glass fiber matlaid in a casting container until the glass fiber mat was submerged. Thecommercial glass fiber mat, trade name KOBEMAT®, was procured fromKOBE-cz s.r.o. (Brno-Country District, Czech Republic) and includedneedle-punched glass fibers, average fiber length of 50 mm and averagefiber diameter of 12 μm. The cast gel precursor was held at about 85° C.for three days to gel. After the gel was set, the fiber-reinforced wetgel was removed from the casting container and submerged in acetone forthree days at room temperature, with acetone exchanges every 12 hours.After solvent exchange, the gel was dried by 85° C. for two days undervacuum.

The thermal conductivity was measured at a mean temperature of 20° C.and 13.8 kPa pressure using a heat flow meter (HFM). Thermalconductivity of the glass fiber-reinforced resorcinol formaldehydeaerogel blankets of the present invention with the indicated R/C valueare listed in Table 4.

TABLE 4 Sample Thermal conductivity No R/C (mW/m · K) 1 100 31 2 400 29

Example 5 Polyester Fiber-Reinforced Mixed-Catalyst ResorcinolFormaldehyde Aerogels

Polyester fiber-reinforced resorcinol formaldehyde aerogels wereproduced in which the molar ratio of resorcinol to catalyst (R/C) in thegel precursor was 400, 500, 600, 650, or 700. The catalyst was a mixtureof calcium carbonate and sodium carbonate at a Ca:Na weight ratio of3(Ca):1(Na) or 1(Ca):1(Na). The total solids content in the gelprecursors (i.e., resorcinol, formaldehyde, and carbonate) was at 20%w/v, 25% w/v, or 30% w/v. The molar ratio of resorcinol to formaldehyde(R/F) was fixed at 0.5.

For a chosen R/C ratio, the required resorcinol was placed in a sealablereactor with 50 mL of deionized water and mechanically stirred untilcompletely dissolved. The calcium carbonate was added to the resorcinolsolution with continued stirring until completely dissolved. Therequired volume of 37 wt. % formaldehyde solution and additionaldeionized water to give the total volume of 600 mL at 20%, 25%, or 30%solids was added to the reactor, which was sealed and stirred for 30min. This gel precursor solution was then poured over a 0.5 cm thickpolyester fiber mat laid in a casting container until the fiber mat wassubmerged. The polyester mat, trade name AB10, procured from Cytec®Process Materials (Heanor, Derbyshire, UK) included needle-punchedpolyester fibers, average fiber length of 64 mm and average fiberdiameter of 180 μm. The cast gel precursor was held at about 85° C. forthree days to gel. After three days, the fiber-reinforced wet gel wasremoved from the casting container and submerged in acetone for 3 daysat room temperature, with acetone exchanges every 12 hours. Aftersolvent exchange, the gel was dried by 85° C. for 2 days under vacuum.

The thermal conductivity was measured at a mean temperature of 20° C.and 13.8 kPa pressure with a HFM. The thermal conductivity of PETfiber-reinforced mixed-catalyst resorcinol formaldehyde aerogel blanketswith the indicated R/C value are presented in Table 5. The pore sizedistribution of the samples at a catalyst mixture ratio of 1(Ca):1(Na),R/C 600, and 25% and 30% solids as measured by mercury intrusionporosimetry (MIP) are presented in FIG. 7. MIP was able to measure porediameters larger than 100 nm. FIG. 7 shows multi-modal pore sizedistributions, with substantial populations of pores larger than 100 nm.

TABLE 5 Catalyst mixture ratio Solids Thermal conductivity (w/w) content(%) R/C (mW/m · K) 3(Ca):1(Na) 20 400 28.2 3(Ca):1(Na) 20 500 28.53(Ca):1(Na) 30 400 26.2 3(Ca):1(Na) 30 500 26.7 3(Ca):1(Na) 30 600 28.61(Ca):1(Na) 25 500 26.7 1(Ca):1(Na) 25 600 25.3 1(Ca):1(Na) 25 650 25.41(Ca):1(Na) 25 700 25.9 1(Ca):1(Na) 30 650 24.9 1(Ca):1(Na) 30 700 24.5

Example 6 Vacuum Insulation Panel Using Fiber-Reinforced Mixed-CatalystResorcinol Formaldehyde Aerogels

Vacuum insulation panels (VIP) using fiber-reinforced resorcinolformaldehyde aerogels as a core were produced in which thepolyester-reinforced mixed catalyst resorcinol formaldehyde aerogelswere vacuum sealed in a polyester bag. Sealing at 60 mbar was achievedby subjecting the bagged blanket under vacuuming for 5 minutes andsealing at 50 mbar was reached by subjecting the bagged blanket undervacuuming for 12 hours.

The molar ratio of resorcinol to catalyst (R/C) in the gel precursor was650. The catalyst was a mixture of calcium carbonate and sodiumcarbonate at a weight ratio of 1(Ca):1(Na). The total solids content inthe gel precursors (i.e., resorcinol, formaldehyde, and carbonate) wasat 30% w/v. The molar ratio of resorcinol to formaldehyde (R/F) was at0.5. The polyester-reinforced resorcinol formaldehyde aerogels wereproduced following the same procedure as Example 5.

The thermal conductivity was measured at a mean temperature range of−20° C. to 70° C. and 13.8 kPa pressure with a heat flow meter (HFM).The thermal conductivity of vacuum insulation panels using PETfiber-reinforced mixed-catalyst resorcinol formaldehyde aerogel of thepresent invention with the indicated R/C value are presented in Table 6and FIG.

TABLE 6 Mean Thermal conductivity temperature (° C.) (mW/m · K) −20 17.5−10 18.2 0 19.2 10 20.1 20 20.9 30 21.9 40 22.8 50 23.7 60 24.8 70 26.0

Example 7 Mechanical Properties of Polyester Fiber-Reinforced ResorcinolFormaldehyde Aerogels of the Present Invention

Polyester Fiber-reinforced organic polymer aerogels were produced bymethods similar to those in Examples 3. The mechanical properties of theproduced aerogels were measured in tension, flexure, and compression byfollowing standard testing procedures ASTM D5035 and ASTM C165 at atemperature of 23° C. The mechanical results are summarized in Tables 7,8 and 9 in comparison with the similar measurement obtained from acommercial silica aerogel based blanket. Table 7 lists tensileproperties of the polyester fiber-reinforced resorcinol formaldehydeaerogel blanket of the present invention. Table 8 lists flexureproperties of the polyester fiber-reinforced resorcinol formaldehydeaerogel blanket of the present invention. Table 9 lists compressiveproperties of the polyester fiber-reinforced resorcinol formaldehydeaerogel blanket of the present invention. Commercial silica aerogelbased blanket is subject to severe dustiness when the blanket ismechanical handled. Since the polyester-reinforced resorcinolformaldehyde aerogel blanket of the present invention exhibitssignificantly better mechanical performance, the dustiness was expectedto be reduced. To demonstrate this, the aerogel blanket of the presentinvention and a commercial silica gel aerogel blanket were used torepeatedly fully wrap around a 20 cm long steel pipe with an outerdiameter of 10 cm. The weight change after each wrapping was measuredusing a microbalance and the weight loss as a function of the number ofrepeated wrapping is presented in FIG. 9. Data line 90 is thepolyester-reinforced resorcinol formaldehyde aerogel blanket of thepresent invention. Data line 92 is the commercial silica aerogelblanket. From the data, it was determined that the aerogel blanket ofthe present invention a minimal weight change while the commercialaerogel blanket had a significant weight change.

TABLE 7 Machine Machine Cross Cross UTS Modulus UTS Modulus (MPa) (MPa)(MPa) (MPa) Example 7 4.9 57.9 2.1 41.8 Blanket Commercial 0.4 15.6 0.16.1 Silica Aerogel Blanket

TABLE 8 Stress at 10% Strain Stress at 10% Strain (MPa) (MPa) Example 71.56 2.22 Blanket Commercial 0.02 0.05 Silica Aerogel Blanket

TABLE 9 Stress at 10% Stress at strain (MPa, 20% strain Modulus 23° C.)(MPa, 23° C.) (MPa, 23° C.) Example 7 Blanket 0.85 1.75 6.40 CommercialSilica 0.01 0.11 0.33 Aerogel Blanket

1. A fiber-reinforced aerogel comprising a porous organic polymer matrixand fibers comprised in the porous organic polymer matrix, wherein theaerogel comprises: a thermal conductivity of less than or equal to 60mWIm·K at a temperature of 20° C.; at least a bimodal pore sizedistribution with a first mode of pores having an average pore size ofless than or equal to 50 nanometers (nm) and a second mode of poreshaving an average pore size of greater than 50 nm; and a planar shapehaving a thickness of 5 millimeters (mm) or less and is capable of beingrolled up into a roll, wherein the fibers form a woven fiber matrix. 2.The fiber-reinforced aerogel of claim 1, wherein the first mode of poreshas an average pore size from 3 nm to 50 nm and the second mode of poreshas an average pore size greater than 50 nm to 10 μm.
 3. Thefiber-reinforced aerogel of claim 1, wherein a weight ratio of theporous organic polymer matrix to the fibers is 50:1 to 65:1.
 4. Thefiber-reinforced aerogel of claim 1, wherein the porous organic polymermatrix comprises resorcinol formaldehyde, phenol formaldehyde,polyimide, polyamine, polyamide, poly(amide-imide), poly(amic amide),poly(ether imide), polyphenol, polyalcohol, polyvinyl butryal,polyurethane, polyurea, polycarbonate, polyester, polyether, polyacid,or any combination thereof.
 5. The fiber-reinforced aerogel of claim 4,wherein the porous organic polymer matrix comprises resorcinolformaldehyde.
 6. The fiber-reinforced aerogel of claim 4, wherein theporous organic polymer matrix comprises polyimide.
 7. Thefiber-reinforced aerogel of claim 1, wherein the fibers comprisevegetable fibers, wood fibers, animal fibers, mineral fibers, orbiological fibers, or any combination thereof.
 8. The fiber-reinforcedaerogel of claim 1, wherein the fibers comprise rayon fibers, bamboofibers, diacetate fibers, triacetate fibers, polyester fibers, or aramidfibers, or any combination thereof.
 9. The fiber-reinforced aerogel ofclaim 1, wherein the fibers are polyester fibers or polyethyleneterephthalate fibers or a combination thereof.
 10. The fiber-reinforcedaerogel of claim 1, wherein the fibers comprise metal fibers, carbonfibers, carbide fibers, glass fibers, mineral fibers, or basalt fibers,or any combination thereof.
 11. The fiber-reinforced aerogel of claim 1,wherein the fibers comprise glass fibers.
 12. The fiber-reinforcedaerogel of claim 1, wherein the fibers comprise thermoplastic polymerfibers or thermoset polymer fibers, or a combination thereof.
 13. Thefiber-reinforced aerogel of claim 12, wherein the thermoplastic polymerfibers are fibers of polyethylene terephthalate (PET), a polycarbonate(PC) family of polymers, polybutylene terephthalate (PBT),poly(1,4-cyclohexylidene cyclohexane-1,4-dicarboxylate) (PCCD), glycolmodified polycyclohexyl terephthalate (PCTG), poly(phenylene oxide)(PPO), polypropylene (PP), polyethylene (PE), polyvinyl chloride (PVC),polystyrene (PS), polymethyl methacrylate (PMMA), polyethyleneimine orpolyetherimide (PEI) and their derivatives, thermoplastic elastomer(TPE), terephthalic acid (TPA) elastomers, poly(cyclohexanedimethyleneterephthalate) (PCT), polyethylene naphthalate (PEN), polyamide (PA),polysulfone sulfonate (PSS), sulfonates of polysulfones, polyether etherketone (PEEK), polyether ketone (PEKK), acrylonitrile butyldiene styrene(ABS), or polyphenylene sulfide (PPS), or co-polymers thereof, or blendsthereof.
 14. The fiber-reinforced aerogel of claim 12, wherein thethermoset polymer fibers are fibers of polyaramid, polyimide,polybenzoxazole, or polyurethane, or any combination thereof.
 15. Thefiber-reinforced aerogel of claim 1, wherein the porous organic polymermatrix is cross-linked.
 16. The fiber-reinforced aerogel of claim 1,wherein the aerogel has a density of 0.1 g/cm³ to 0.5 g/cm³.
 17. Thefiber-reinforced aerogel of claim 1, wherein the aerogel has a porevolume of greater than 2 cm³/g or a surface area of at least 150 m²/g.18. The fiber-reinforced aerogel of claim 1, wherein the aerogel has athickness of 0.5 mm to 5 mm.
 19. The fiber-reinforced aerogel of claim1, wherein the aerogel has a thickness of 0.5 mm to 2 mm.
 20. Thefiber-reinforced aerogel of claim 1, wherein the aerogel site has a flexfatigue of at least 100,000 cycles to failure or a tensile strength ofat least 2 MPa.
 21. The fiber-reinforced aerogel of claim 1, wherein theaerogel has less than 0.5 weight percent change when wrapped around apipe having a diameter of 10 centimeters (cm).
 22. An article ofmanufacture comprising the fiber-reinforced aerogel of claim
 1. 23. Thearticle of manufacture of claim 22, wherein the article of manufactureis a monolith, a wafer, a blanket, a core composite material, asubstrate for a radiofrequency antenna, a sunscreen, a sunshield, aradome, a support for a catalyst, or a support for a drug,pharmaceutical, and/or drug delivery system.
 24. The article ofmanufacture of claim 22, wherein the article of manufacture is afiltration apparatus.
 25. The article of manufacture of claim 22,wherein the article of manufacture is an insulation material.
 26. Thearticle of manufacture of claim 25, wherein the insulation material isfor an oil and/or gas pipeline, a liquefied natural gas pipeline, acryogenic fluid transfer pipeline, an apparel, an aerospace application,a building, a car, an automotive application, a radiator, ducting andventilation, air conditioning, heating and refrigeration, a mobile airconditioning unit, a cooler, packaging, a consumer good, a vibrationdampening material, a wire or cable, or a medical device.